­If you live in a city that gets lots of snow and ice, then you're familiar with road salt. Your city and local government likely has several de-icing trucks that spread road salt on the highways, streets and sidewalks to melt the ice.­ But how exactly does it work? First, road salt is simply ...

Salt melts ice essentially because adding salt lowers the freezing point of the water. How does this melt ice? Well, it doesn't, unless there is a little water available with the ice. The good news is you don't need a pool of water to achieve the effect. Ice typically is coated with a thin film of liquid water, which is all it takes.

Not because the rock salt will stop working, but more for the refreeze concern. Once the salt melts the snow, ambient temperature becomes an important factor, because it will freeze that nice melted snow into a nice shiny sheet of ice real quick if it's just NaCl brine.

At what temperature does salt melt ice? At a temperature of 30 degrees (F), one pound of salt (sodium chloride) will melt 46 pounds of ice. But, as the temperature drops, salt's effectiveness slows to the point that when you get down near 10 degrees (F) and below, salt is barely working. 1

Although not frequently used as rock salt, ordinary table salt too can be used to melt ice. In fact, it is far more effective than rock salt at melting ice.. How Table Salt Melts Ice. Like other substances used for melting ice, table salt melts ice by lowering its freezing point.

Pour cold water, ice, and salt into the cooler to create a salt-water-ice bath. Why does it work? The ice will be at a temperature way below zero, usually -18°C for a household freezer [2]. The ice will cool the water down and the salt will allow the water temperature to drop below 0°C.

-10F to -15F. Where I live ( central Canada) we never use salt and have not for years. It's just a waste of money because it doesn't work. And the colder it get the less slippery ice gets, so traction is not really a big problem here. Road crews use a minimum amount of sand except at intersections. The major benefit is that our cars last forever.